1. Field of the Invention
The present invention relates to an X-ray computed tomographic apparatus, breath instruction apparatus, and medical imaging apparatus which generate medical images by imaging a subject to be examined.
2. Description of the Related Art
Stable breathing is indispensable for improving image quality by reducing artifacts. Conventionally, in order to stabilize breathing motion, an operator gives a subject to be examined spoken instructions from an operator room through a microphone. It is, however, difficult to stabilize breathing motion by spoken instructions. Furthermore, an operator who has not comprehended the stable breathing of a subject may unstabilize the breathing of the subject by giving him/her inappropriate instructions. See Jpn. Pat. Appln. KOKAI Publication No. 2003-265464.
Conventionally, an X-ray computed tomographic apparatus uses an imaging method and reconstruction method which require the electrocardiographic complex of a subject, such as an ECG-gated scanning method and an ECG-gated reconstruction method. However, a conventional X-ray computed tomographic apparatus does not allow to check how electrocardiograms have been captured, and hence may not be properly ECG-gated. In operation except ECG-gated imaging or ECG-gated reconstruction, it is preferable in terms of reduction in artifacts to perform scanning in a period during which the heart rate is stable. It is, however, impossible to check this. The operator therefore starts scanning upon determining a stable period by checking the heart rate according to his/her experience. See Jpn. Pat. Appln. KOKAI Publication No. 2003-265464.
In addition, conventionally, a subject is instructed by voice how to act during examination. For example, the automatic voice playback device of an apparatus gives a spoken instruction to hold a breath or a spoken instruction not to move, or the operator gives such instructions by human voice through a microphone. The subject totally depends on voice when acquiring information, and cannot know any information about the remaining time of breath holding, the remaining time of examination, and the like without voice. This may cause a situation in which the subject feels insecure. In addition, in imaging operation, it is preferable in term of reduction in body movement artifacts that a subject keeps quiet and relaxed and stabilizes his/her heartbeat and breath as much as possible. However, conventional apparatuses have not been provided with any techniques for making subjects feel relaxed. See Jpn. Pat. Appln. KOKAI Publication No. 2003-265464.